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Science of empirical design in mining ground control

International journal of Mining Science and Technology 2016年第3期26卷 461-470页

作者： mark Christopher MSHA Pittsburgh Safety & Health Technology Center

Many problems in rock engineering are limited by our imperfect knowledge of the material properties and failure mechanics of rock masses. Mining problems are somewhat unique, however, in that plenty of real world experience is generally available and can be turned into valuable experimental *** pillar that is developed, or stope that is mined, represents a full-scale test of a rock mechanics design. By harvesting these data, and then using the appropriate statistical techniques to interpret them,mining engineers have developed powerful design techniques that are widely used around the *** empirical methods are readily accepted because they are simple, transparent, practical, and firmly tethered to reality. The author has been intimately associated with empirical design for his entire career, but his previous publications have described the application of individual techniques to specific problems. The focus of this paper is the process used to develop a successful empirical method. A sixstage process is described: identification of the problem, and of the end users of the final product; development of a conceptual rock mechanics model, and identification of the key parameters in that model;identification of measures for each of the key parameters, and the development of new measures(such as rating scales) where necessary; data sources and data collection; statistical analysis; and packaging of the final product. Each of these stages has its own potential rewards and pitfalls, which will be illustrated by incidents from the author's own experience. The ultimate goal of this paper is to provide a new and deeper appreciation for empirical techniques, as well as some guidelines and opportunities for future developers.

关键词： Design Pillar Stope Empirical Statistics Modeling

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Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

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Nano Research 2014年第1期7卷 1-62页

作者： mark j. Armstrong Colm O'Dwyer William j. Macklin justin. D. Holmes Materials Chemistry & Analysis Group Department of Chemistry and the Tyndall National Institute University College Cork Cork Ireland Applied Nanoscience Group Department of Chemistry and the Tyndall National Institute University College Cork Cork Ireland Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) Trinity College Dublin Dublin 2 Ireland Nexeon Limited Abingdon Oxfordshire UK.

The performance of the lithium-ion cell is heavily dependent on the ability of the host electrodes to accommodate and release Li＋ ions from the local structure. While the choice of electrode materials may define parameters such as cell potential and capacity, the process of intercalation may be physically limited by the rate of solid-state Li＋ diffusion. Increased diffusion rates in lithium-ion electrodes may be achieved through a reduction in the diffusion path, accomplished by a scaling of the respective electrode dimensions. In addition, some electrodes may undergo large volume changes associated with charging and discharging, the strain of which, may be better accommodated through nanostructuring. Failure of the host to accommodate such volume changes may lead to pulverisation of the local structure and a rapid loss of capacity. In this review article, we seek to highlight a number of significant gains in the development of nanostructured lithium-ion battery architectures （both anode and cathode）, as drivers of potential next-generation electrochemical energy storage devices.

关键词： lithium ion batteries nanostructuring anodes cathodes

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Nogo-A receptor internalization by cyclic adenosine monophosphate in overcoming axonal growth inhibitors after stroke

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Neural Regeneration Research 2022年第1期17卷 91-92页

作者： Rayudu Gopalakrishna Charlotte Lin mark S.Kindy William j.Mack Department of Integrative Anatomical Sciences Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCAUSA Department of Neurological Surgery Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCAUSA Department of Pharmaceutical Sciences College of PharmacyUniversity of South FloridaTampaFLUSA

Currently,there are no clinically proven drugs for recovery from stroke and other neuronal injuries such as traumatic brain injury and spinal cord *** therapy requires axonal regeneration,which is inhibited by diverse axonal growth inhibitors,such as Nogo-A,myelin-associated glycoprotein(MAG),oligodendrocyte myelin glycoprotein(OMgp),and chondroitin sulfate proteoglycans(CSPGs)(Chaudhry and Filbin,2007;Carmichael,2010;Schwab and Strittmatter,2014).

关键词： axonal injuries inhibited

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Avalonia,get bent!–Paleomagnetism from SW Iberia confirms the Greater Cantabrian Orocline

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Geoscience Frontiers 2021年第2期12卷 805-825页

作者： Bruno Daniel Leite Mendes Daniel Pastor-Galan mark j.Dekkers Wout Krijgsman Paleomagnetic Laboratory Fort Hoofddijk Department of Earth SciencesUtrecht UniversityBudapestlaan 173584CDthe Netherlands Frontier Research Institute for Interdisciplinary Sciences Tohoku UniversityJapan Department Earth Science Tohoku UniversityJapan Center for North East Asia Studies Tohoku University980-857641 KawauchiAoba-kuSendaiMiyagiJapan

The amalgamation of Pangea formed the contorted Variscan-Alleghanian orogen,suturing Gondwana and Laurussia during the *** all swirls of this orogen,a double curve in Iberia stands out,the coupled Cantabrian Orocline and Central Iberian *** Cantabrian Orocline formed at ca.315–290 Ma subsequent to the Variscan *** formation mechanism of the Cantabrian Orocline is disputed,the most commonly proposed mechanisms include either(1)that south-westernmost Iberia would be an Avalonian(Laurussian)indenter or(2)that the stress field changed,buckling the *** contrast,the geometry and kinematics of the Central Iberian curve are largely *** some authors defend both curvatures are genetically linked,others support they are distinct and formed at different *** uncertainty adds an extra layer of complexity to our understanding of the final stages of Pangea’s *** solve these issues,we study the late Carboniferous–early Permian vertical-axis rotations of SW Iberia with *** results show up to 70counterclockwise vertical-axis rotations during late Carboniferous times,concurring with the anticipated kinematics if SW Iberia was part of the southern limb of the Cantabrian *** results do not allow the necessary penecontemporaneous clockwise rotations in Central Iberia to support a concomitant formation of both Cantabrian and Central Iberian *** coherent rotation of both Gondwanan and Avalonian pieces of SW Iberia discards the Laurussian indenter hypothesis as a formation mechanism of the Cantabrian Orocline and confirms the Greater Cantabrian Orocline *** Greater Cantabrian Orocline likely formed as a consequence of a change in the stress field during the late Carboniferous and extended beyond the Rheic Ocean suture affecting the margins of both Laurussia and Gondwana.

关键词： Pangea Variscan orogeny Greater Cantabrian Orocline Paleomagnetism Central Iberian curve

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Unanticipated multiple seam stresses from pillar systems behaving as pseudo gob–case histories

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International journal of Mining Science and Technology 2017年第1期27卷 131-137页

作者： Gauna Michael mark Christopher Pittsburgh Safety and Health Technology Center Mine Safety and Health Administration(MSHA)PittsburghPA 15236USA

Underground coal mining in the U.S. is conducted in numerous regions where previous workings exist above and/or below an actively mined seam. Miners know that overlying or underlying fully extracted coal areas, also known as gob regions, can result in abutment stresses that affect the active mining. If there was no full extraction, and the past mining consists entirely of intact pillars, the stresses on the active seam are usually minimal. However, experience has shown that in some situations there has been sufficient yielding in overlying or underlying pillar systems to cause stress transfer to the adjoining larger pillars or barriers, which in turn, transfer significant stresses onto the workings of the active seam. In other words, the overlying or underlying pillar system behaves as a ‘‘pseudo gob." The presence of a pseudo gob is often unexpected, and the consequences can be severe. This paper presents several case histories, summarized briefly below, that illustrate pseudo gob phenomenon:(1) pillar rib degradation at a West Virginia mine at 335 m depth that contributed to a rib roll fatality,(2) pillar rib deterioration at a Western Kentucky mine at 175 m depth that required pillar size adjustment and installation of supplemental bolting,(3) roof deterioration at an eastern Kentucky mine at 400 m depth that stopped mine advance and required redirecting the section development,(4) coal burst on development at an eastern Kentucky mine at 520 m depth that had no nearby pillar recovery, and(5) coal burst on development at a West Virginia mine at the relatively shallow depth of 335 m that also had no nearby pillar recovery. The paper provides guidance so that when an operation encounters a potential pseudo gob stress interaction the hazard can be mitigated based on an understanding of the mechanism encountered.

关键词： Underground mining Coal Multiple seam Gob Ground control

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Preventing roof fall fatalities during pillar recovery:A ground control success story

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International journal of Mining Science and Technology 2017年第1期27卷 107-113页

作者： mark Christopher Gauna Michael MSHA Pittsburgh Safety and Health Technology CenterPittsburghPA 15236USA

For decades, pillar recovery accounted for a quarter of all roof fall fatalities in underground coal *** showed that a miner on a pillar recovery section was at least three times more likely to be killed by a roof fall than other coal miners. Since 2007, however, there has been just one fatal roof fall on a pillar line. This paper describes the process that resulted in this historic achievement. It covers both the key research findings and the ways in which those insights, beginning in the early 2000 s, were implemented in mining practice. One key finding was that safe pillar recovery requires both global and local *** stability is addressed primarily through proper pillar design, and became a major focus after the2007 Crandall Canyon mine disaster. But the most significant improvements resulted from detailed studies that showed that local stability, defined as roof control in the immediate work area, could be achieved with three interventions:(1) leaving an engineered final stump, rather than extracting the entire pillar,(2) enhancing roof bolt support, particularly in intersections, and(3) increasing the use of mobile roof supports(MRS). A final component was an emphasis on better management of pillar recovery *** included a focus on worker positioning, as well as on the pillar and lift sequences, MRS operations,and hazard identification. As retreat mines have incorporated these elements into their roof control plans,it has become clear that pillar recovery is not ‘‘inherently unsafe." The paper concludes with a discussion of the challenges that remain, including the problems of rib falls and coal bursts.

关键词： Retreat mining Roof support Room-and-pillar Ground control

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Plasmonic group 4 transition metal carbide interfaces for solar-driven desalination

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Aggregate 2024年第4期5卷 147-154页

作者： Matthew j.Margeson mark Atwood Yashar Esfahani Monfared Mita Dasog Department of Chemistry Dalhousie UniversityHalifaxCanada

To combat the dwindling supply of freshwater,solar-driven desalination using plas-monic nanomaterials has emerged as a promising and renewable *** plasmonic carbide nanomaterials are exciting candidates that are inexpensive and chemically robust but have not been widely ***,plasmonic car-bide interfaces made of TiC,ZrC,and HfC nanoparticle aggregates loaded onto to a mixed cellulose ester(MCE)membrane were explored to gain insight into their solar-vapor generation and desalination *** using Atlantic Ocean water under 1 sun intensity yielded rates of 1.260.01,1.180.02,and±±1.400.01 kg±m-2 h-1,with efﬁciencies of 86%,80%,and 96%for TiC,ZrC,and HfC,*** interfaces showed good stability and effectively removed heavy metal ions and salt from solutions with concentrations up to 35%.PVA hydro-gel based TMC evaporators afforded rates of 3.310.03 and 3.220.03 kg±±m-2h-1 for TiC and ZrC,*** HfC-PVA interface afforded a high solar desalination rate of 3.690.04 kg±m-2 h-1,corresponding to an efﬁciency of 97%under 1-sun *** hydrogel evaporators also retained their strong salt rejection action over time.

关键词： carbides desalination photothermal plasmonics water evaporation

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An in situ monitoring campaign of a hard rock pillar at great depth within a Canadian mine

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journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 427-448页

作者： Bradley Forbes Nicholas Vlachopoulos mark S.Diederichs Andrew j.Hyett Allan Punkkinen Department of Geological Sciences and Geological Engineering Queen’s UniversityKingstonOntarioK7L 3N6Canada Department of Civil Engineering Royal Military College of CanadaKingstonOntarioK7K 7B4Canada YieldPoint Inc. KingstonOntarioK7M 4W9Canada Normet Canada Ltd. LivelyOntarioP3Y 0B3Canada

A recent research campaign at a Canadian nickel-copper mine involved instrumenting a hard rock sill drift pillar with an array of multi-point rod extensometers,distributed optical fibre strain sensors,and borehole pressure cells(BHPCs).The instrumentation spanned across a 15.24 m lengthwise segment of the relatively massive granitic pillar situated at a depth of 2.44 km within the *** May 2016 and March 2017,the pillar’s displacement and pressure response were measured and correlated with mining activities on the same level as the pillar,including:(1)mine-by of the pillar,(2)footwall drift development,and(3)ore body stoping *** displacements of the pillar,the extensometers provided high temporal resolution(logged hourly)and the optical fibre strain sensors provide high spatial resolution(measured every 0.65 mm along the length of each sensor).The combination of sensing techniques allowed centimetre-scale rock mass bulking near the pillar sidewalls to be distinguished from microstrain-scale fracturing towards the core of the ***,the influence and extent of a mine-scale schistose shear zone transecting the pillar was *** converting measured rock mass displacement to velocity,a process was demonstrated which allowed mining activities inducing displacements to be categorised by time-duration and cumulative *** over half of the analysed mining activities,displacements were determined to prolong for over an hour,predominately resulting in submillimetre cumulative displacements,but in some cases multi-centimetre cumulative displacements were *** time-dependent behaviour was more pronounced within the vicinity of the plumb shear *** measurements were also used to assess selected support member load and elongation mobilisation per mining *** was found that a combined static load and elongation capacity of reinforcing members was essential to maintaining excavation stability,while

关键词： Hard rock pillar Rockburst Rock mass bulking Distributed optical fibre strain sensing Extensometer In situ monitoring High stress Dynamic support

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Fluidization and bubbling behavior of potash particles in a deep fluidized bed

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Particuology 2023年第9期80卷 103-114页

作者： Mojtaba Nabipoor Hassankiadeh jingsi Yang mark Berrey Dave jordison Lifeng Zhang Donald Bergstrom Raymond j.Spiteri Department of Chemical and Biological Engineering University of SaskatchewanSKS7N 5A9SaskatoonCanada The Mosaic Company Belle PlaineSKCanada Department of Mechanical Engineering University of SaskatchewanSaskatoonCanada Department of Computer Science University of SaskatchewanSaskatoonSKCanada

Most existing models for predicting bubble size and bubble frequency have been developed for freely bubbling fluidized *** prediction of bubbling behavior in deep fluidized beds,however,has been a challenge due to the higher degree of bubble coalescence and break up,high probability of the slugging regime,partial fluidization,and chaotic behavior in the bubbling *** this work,the bubbling and fluidization behavior of potash particles was investigated in a deep fluidized bed employing a twin-plane electrical capacitance tomography(ECT)*** volume fraction,average bubble velocity,average bubble diameter,and bubble frequency in both bubbling and slugging regimes were measured at two different bed height ratios(H/D=3.5 and H/D=3.78).This work is the first to illustrate a sequential view of bubbles at different superficial gas velocities in a fluidized *** results show that both the bubble diameter and rising velocity increased with increasing the superficial gas velocity for the two bed heights,with larger values observed in the deeper bed compared to the shallower *** values for bubble diameter,bubble rise velocity and bubble frequency from different models are compared with the experimental data obtained from the ECT system in this *** agreement has been achieved between the values predicted by the previous models and the experimental data for the bubble diameter and bubble rise velocity with an average absolute deviation of 16%and 15%for the bed height of 49 cm and 13%and 8%for the bed height of 53 cm,respectively.

关键词： Deep fluidized bed Potash particle Electrical capacitance tomography Image reconstruction Bubbling and slugging regime

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What diameter?What height?Influence of measures of average tree size on area-based allometric volume relationships

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Forest Ecosystems 2024年第1期11卷 100-109页

作者： Yilin Wang john A.Kershaw mark j.Ducey Yuan Sun james B.McCarter Integrated Forest Mensuration and Systems Analysis Laboratory Faculty of Forestry and Environmental ManagementUniversity of New BrunswickFrederictonNBCanada Department of Natural Resources and the Environment University of New HampshireDurhamNHUSA College of Forestry Nanjing Forestry UniversityNanjing210037China Scientific Programmer RayonierYuleeFLUSA

Volume is an important attribute used in many forest management *** from 83 fixed-area plots located in central New Brunswick,Canada,are used to examine how different measures of stand-level diameter and height influence volume prediction using a stand-level variant of Honer's(1967)volume *** density was included in the models(Volume=f(Diameter,Height,Density))choice of diameter measure was more important than choice of height *** density was not included(Volume=f(Diameter,Height)),the opposite was *** models with density included,moment-based estimators of stand diameter and height performed better than all other *** models without density,largest tree estimators of stand diameter and height performed better than other *** overall best equation used quadratic mean diameter,Lorey's height,and density(root mean square error=5.26 m^3·ha^(-1);1.9%relative error).The best equation without density used mean diameter of the largest trees needed to calculate a stand density index of 400 and the mean height of the tallest 400 trees per ha(root mean square error=32.08 m^(3)·ha^(-1);11.8%relative error).The results of this study have some important implications for height subsampling and LiDAR-derived forest inventory analyses.

关键词： Allometric relationships Stand structure Volume estimation Stand-level attributes

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